This invention relates to a substantially leakproof container. The body of the container is constructed from a unitary, thermoplastic coated paperboard blank, and two end closure members seal the container formed from the blank. This invention particularly relates to a container provided with a base portion of improved strength and durability which enables the container to maintain its substantially leakproof condition should the container, when filled, be dropped on its base portion during transport or storage.
While numerous articles may be packaged in this container, it is particularly useful in the packaging of materials that require enclosure within a container having good moisture barrier properties. In particular, this container is adapted for the shipment and storage of frozen liquids, liquid materials, and moisture sensitive materials.
In certain industries, it is common to package a liquid material in a container, freeze the liquid material within the container, and ship the frozen material, still within the original container, to the user. The user then stores the frozen material until the material is needed, at which time the user defrosts the material. For example, it is a common practice for bakeries that bake goods on a large scale for distribution to retail outlets to buy pails of raw, shelled eggs. Such eggs are purchased from dairy processors, who shell the eggs and then pour the shelled eggs into a pail that holds approximately thirty pounds of eggs. The eggs, which are then sealed in the pail, are frozen or "blast frozen" and shipped in the frozen state to the baked goods manufacturer. At the bakery, the frozen eggs, still in the original, shipping container, are kept in frozen storage until they are required for use. When it is necessary to use the eggs, the container is removed from the freezer, and the eggs are allowed to be defrosted so that they return to the liquid state. Obviously, if the shipping container has been dropped on its base portion at any time during its transport or storage, as the frozen material returns to the liquid state, it may leak through the cracks in the container. Also, while the material is still in the frozen state, if the container has been dropped and its external surface has been fractured, the product within the container may become contaminated.
At the present time, there are several methods used in the packaging of liquid materials, such as eggs, that are subsequently frozen, shipped, and then defrosted prior to use. One approach employs metal pails; a second approach employs solid plastic pails. Containers made from these materials, however, are expensive and may be subject to fracture. It has been found, for example, that when a metal pail filled with the frozen material is dropped, the welded side seam, or the welded joint that encircles the base portion of the pail, may have a tendency to split. Solid plastic pails may fracture at the area of impact.
Paperboard containers, having at least one upper or lower closure member, for containing liquids are generally known in the art. See, for example, U.S. Pat. Nos. 1,968,270; 2,058,592; 2,097,893; 2,125,417; and 2,416,813. None of these references, however, discloses a container adapted for use in an industry where large or heavy amounts of liquid materials are required to be packaged, frozen, transported over distances, stored and defrosted, all within the original packaging container. Such an industry requires a relatively inexpensive container that can be assembled automatically, quickly filled with the goods to be shipped, sealed, placed in vertical stacks during its shipping and storage periods, and can still maintain its substantially leakproof condition when subjected to rough handling and dropping during its transport or storage. In addition, such a container must be suitable to allow the goods to be defrosted therewithin when they are required to be used.